Means for increasing the subterranean flow into and from wells



Aug. 24-, 1954 N. B. DISMUKES 2,537,179

MEANS FOR INCREASING THE SUBTERRANEAN FLOW INTO AND FROM WELLS Filed Aug. 26, 1948 4 Sheets-Sheet l 7O 60 IN VENTOR. Newton B. Dlsrnukes 20+ 12 1a lg W g 6 ATTORNEYS.

Aug. 24, 1954 N. B. DISMUKES 2,537,179

I MEANS FOR INCREASING THE SUBTERRANEAN FLOW INTO AND FROM WELLS 4 Sheets-Sheet 2 Filed Aug. 26, 1948 FIG.6.

XNVENTOR.

ATORN E-Y 4, 1954 N. B. DlSMUKES 2,687,179

INCREA SUBT ANEAN MEANS FOR SING THE FLOW INTO AND FROM WEL Filed Aug. 26, 1948 4 Sheets-Sheet 3 ullllllllilfi INVENTOR.

' Newton B. Dismuleas 1a,. a WMQJ ATTORNEYS.

Aug. 24, 1954 N B DISMUKES MEANS FOR INCREASING THE SUBTERRANEAN FLOW INTO AND FROM WELLS Filed Aug. 26, 1948 4 Sheets-Sheet 4 YRk INVENTOR.

Newton B. Dismukes ATTORNEYS.

Patented Aug. 24, 1954 OFFICE MEANS FOR INCREASING THE SUB'EER- RANEAN FLOW INTO AND FROM WELLS Newton B. Dismukes, Tulsa, Okla.

Application August 26, 1M8, Serial No. 46,236

5 Claims. 1

This invention relates to means for increasing the subterranean flow into and from wells. More specifically, it relates to apparatus for rupturing the stratum surrounding a well bore so as to provide fissures, radiating from the bore, thru which he fluid within the strata may flow.

An important object of the invention is to provide apparatus, including an expansible and contractable structure for expansion against the well bore wall so to cause fracturing of the stratum.

Another important object is to provide apparatus for the purpose mentioned which may be employed in well bore-s at depths where temperatures are too high for shooting.

Still another important object is to provide apparatus which may be oriented in a well bore so that at least partial control of the direction of fracturing can be obtained. That is, fractures may be produced, extending into the stratum surrounding the well bore, substantially 180 apart. By a 90 rotation of the apparatus, if desired, other fractures may be produced spaced substantially 90 from the first fractures.

A further important object is to provide such an apparatus which may be positioned to create the fractures at a selected depth or at selected depths.

Fracturing of oil-bearing strata in this manner will have wide application in secondary recovery of oil, especially in water-flooding. Input wells can be made to take larger volumes of water and, if directional fracturing is used between wells, fiooding efficiency will be greatly increased as line drive will be created. In tight (low permeability) sandstones or limestones the fracturing will greatly increase production and oil recovery by primary production methods as the crevices and cracks formed will allow more rapid how of fluid into the bore hole under smaller pressure differentials. In fields having lenticular sands these fractures may cause oil to be produced from lens not otherwise to be opened.

By the employment of the apparatus disclosed, fracturing can be accomplished without the danger or damage to casings which often accompanies shooting and, by the use of the novel apparatus disclosed, there will be no resulting fragments to be removed from the well bore.

I am aware that wedges have been employed in drilled holes to cause splitting of rocks (Peele in Mining Engineering Handbook, John Wiley & Sons, 1927; O. Bowles in The Stone Industries, McGraw Hill Book Co., 1939 pages 88-89; O. Bowles in the Technology of Marble Quarrying,

U. S. B. M. Bulletin, 106, pages '76-'78), but there is no teaching nor hints therein nor in other authorities consulted of the apparatus and method herein disclosed nor of any apparatus constructed and arranged to be introduced into a well bore and manipulated so that portions of the outer wall thereof will be forced against the wall of a well bore to cause fracturing of the stratum surrounding the well bore.

Other objects and advantages of the invention will be apparent during the course of the following detailed description of the invention, taken in connection with the accompanying drawings, forming parts of this disclosure, and in which dra l is a ver tical section of one form of the invention.

is a fragmentary elevation of an intermediate portion of the apparatus showing a support means for expansible and contractable feathers forming a part of the new apparatus and Fig. 3 is a horizontal section substantially on the line 33 of Fig. 2.

Fig. l is a horizontal section substantially on the line 4l of Fig. l.

Fi 5 is elevation of the novel apparatus of Figs. 1 to 4 inclusive positioned within a well bore and in a partly expanded position.

Fig. 6 is a horizontal section on substantially the line 6% of Fig. 5.

Fig. is a View, partly in vertical section and partly elevation of a slip means to anchor the lowered expansible and contractable portions of the novel apparatus.

"ig. 8 is a fragment of the structure of 5 in a supporting position in a well bore.

9 is a View mostly in vertical section of a modified form of the invention within a well bore.

Fig. 10 is a horizontal section on substantially the line iii-i of Fig. 9.

Fig. 11 is a view largely in vertical section of the expansible and contractable structure of a third form of the novel apparatus.

Fig. 12 is a view also largely in vertical section of a pressure fiuicl introducing and discharge means of the form of the invention also disclosed in Fig. 11.

In the drawings, wherein for purpose of illustration are shown preferred and modified forms of the invention and wherein similar reference characters designate corresponding parts thruout the several views, the letter A designates the form of the invention not dependent upon a pressure fluid; 3 a modified iorm, employing a pressure fluid; C a second modified form, also employing a pressure fluid; D a slips support means which may be substituted for the anchoring means of Figs. 1 to 6 inclusive for supporting the lowered expansible and contractable portions of the novel apparatus therein shown, and E designates a well and surrounding stratum.

The form A for fracturing the stratum surrounding a well bore, shown in Figs. 1 to 6 inclusive, comprises an upper rod and hammer structure |5; jar I6 in which portions of the rod and hammer structure reciprocate; a wedge ll, engaging an expansible and contractable structure of feathers l8, means l9 to support the feathers l8; anchoring means 2|] for the feathers l8; and means 2| to aid in removing the apparatus A from a well bore.

Referring mainly to Fig. 1, the upper structure 15 includes a substantially vertically-reciprocating rod 25 and hammer or head 26 with the latter secured, in any approved way, such as by welding, to the lower end portion of the rod. The hammer 26 is preferably of considerable size and weight, such as 4 feet long, 4.5 inches in diameter and weighing about 216 pounds.

The hammer 26 freely reciprocates in jar l6, which latter includes a tubular body portion 30 which may have drain openings 3| suitably spaced along its length to permit the flow of fluid outwardly of the jar l6 and thus not impede reciprocation of the hammer 26. At, preferably, the upper end section of the jar body portion 30 is a suitable abutment 32 such as an inwardlyextending flange, integral with the body portion and constructed and arranged to receive the upward blows of the hammer 25 upon the lower face 33 of the abutment with the abutment extending toward the rod 25. At, preferably, the lower end section of the jar body portion 3|] is a. second abutment 34 which may be a plug, welded, bolted or otherwise firmly secured to the body portion 30. It is preferred that at least the upper end section of this plug be of good spall-resistant steel so as to reduce plastic deformation caused by the blows of the hammer 26 upon its upper face. The jar body portion may be of any suitable length. For example, with the size of hammer as described, this body portion may be feet in length with the inserted abutment 34 about 1 foot long.

Projecting downwardly from and fixedly secured to the abutment 34 is the elongated feathers-engaging wedge I'I. As may be seen, such as in Fig. 6, the wedge preferably includes a pair of opposite, downwardly-converging, substantially fiat faces 46 and a pair of opposite side faces 4| meeting the faces 46 by beveled intermediate faces 42. The expansible and contractable structure comprises two feathers I8 which are substantially alike and each includes a body or wall portion 45 provided with an upwardlyextending half collar 46 whereby a shoulder 41 is provided. Each body portion 45 has an outer, preferably arcuate, peripheral face 48, an inner face 49 with a groove 5|] extending longitudinally of the body portion 45 along the axial center of the face 49 from the upper end of the half collar 46 to the lower end face 5| of the body portion. The lower face 5| is preferably beveled from the outer arcuate face 48 to the inner grooved face 49.

Referring again to the groove 50, it will be noted, as in Fig. 1, that it gradually decreases in depth from the upper end of the half collar 46 to the lower end face 5|. The groove has a substantially flat bottom face 52 to slidably receive 4 the flat face 4| of the wedge l1 and outwardly diverging side faces 53 to slidably receive the beveled face 42 of the wedge.

From the upper end of the half collar 46, downwardly for a relatively short distance (such as approximately 25 inches) a portion of the inner face 49 tapers slightly outwardly and downwardly to meet the remainder of the face 49, this taper being provided to accommodate, in the spaces provided by the tapering of the two inner faces of the assembled feathers, a pair of slots for the accommodation of pins 51 which move along the slots and which will be subsequently described. When the wedge I! is in an inoperative position (as in Fig. l) with respect to the feathers It, the inner faces 49 (except for upper portions thereof) may be in contact.

Means w to support the feathers I8 may be provided by the walls of two cable-accommodating bores 55 extending from the inner face of each half collar 46 to the outer face thereof, substantially as shown in Figs. 2 and 3 and as may be seen, in dotted lines in Fig. 1. These bores 55 (there are four of them in the example of the form A shown) receive the intermediate portions of a suitable cable 56 (such as a quarterinch steel cable) threaded therethru. Associated with the cable 56 are two pins 51 projecting radially, substantially apart, from the wedge l1. These pins 51 are normally disposed above the half collars 46 when the wedge is in the inoperative position (as shown in Fig. 1). Auxiliary pins 55 substantially like the pins 51 may be provided, spaced below the pins 5'! as a safety factor. The cable extends upwardly to and is looped over the pins 51, and its length is such that when the wedge ll is driven downwardly to spread the feathers iii, the cable 56 will be slackened enough to allow the spread. The means Is also function as follows: If, when the wedge ll is drawn upwardly and the feathers do not move toward each other (because they may adhere to the wall of the well bore) the pins will draw the cable 56 taut and, of course, this will cause the feathers to move toward each other and, in addition, to move upwardly. Obviously should the pins 51 break, the auxiliary pins 58 will contact the looped cable and function in their stead.

Anchoring means 26 for the feathers l8 may comprise an elongated pipe 60 provided at its upper end portion with an inwardly-extending projection 6| which may be a flange. This includes an outwardly-and-downwardly-sloping upper face 62 and a substantially horizontal lower face 63. Normally the lower end faces 5| of the feathers rest upon the upper face 62. Extending thru the lower end portions of the feathers are a plurality of horizontally-extending screw threaded bores 64 which align axially with like bores 65 in the projection 6| and receive screws 66. These screws may be of Phosphor bronze and their function are to hold the pipe 65 attached to the feathers it during lowering. This construction restrains the downward and outward movements of the feathers until they are in position to be forced against the wall of the bore. However, the screws 66 are adapted to shear as the wedges I8 separate. This is effected of course, by blows upon the upper face of the lower abutment 34 of the jar l6 which cause the wedge to be driven downwardly, and the downwardly and outwardly sloping upper faces 62 of the projection 6| of the pipe 66, over which the lower end faces 5| of the feathers l6 slide.

The bottom end of the pipe 60 may be closed,

.5 as at 67, and rests upon a suitable base, such as the bottom of the well bore.

This anchoring means 20 serves mainly to support the structure above it only until the feathers l8 separate and are forced against the wall of the bore whereupon the means receive substantially none of the force of the blows of the hammer 20.

Associated with the wedge .7 is means 21 to aid in removing the apparatus A from the bore in the event the feathers it? become stuck in the bore. This comprises a suitable abutment member, as the plate 70 which includes an outer substantially flat horizontally extending portion ll and a socketed central portion 72 receiving the extreme lower end portion of the wedge l7 and to which it may be secured, as by screws 73. The plate portion "it extends outwardly a sufficient distance so that it will, upon upward movement of the wedge, contact t. e lower face 03 of the projection iii of the anchoring means and further upward movement will tend to draw the entire tool A upwardly.

The rod 25 may be reciprocated by any suitable means, such as a cable (not shown) extending to the surface and there operatively connected, for example, to a conventional cable-tool drilling rig (not shown). During lowering of the apparatus A for positioning in the bore 30 of the well E, the feathers is will not spread, as is now apparent. When the closed bottom of the pipe reaches the bottom 8! of the well for example, the apparatus is in a position to be operated. As the reciprocating hammer 2d strikes repeated blows upon the second abutment 30 of the jar IS, the wedge l7 connected with the head will be forced downwardly and cause the feathers H! to move outwardly, pressing against the side wall 82 of the bore 80 and causing cracks or fissures 85 such as shown, by way of example in Figs. 3 and 4 in the stratum 36. These fissures will extend radially and, generally, with their longitudinal axes substantially 180 apart, and permit the flow of fluid which, otherwise, could not readily flow thru the stratum. Of course, the width and length of the fissures will vary, depending upon the compositions of the stratum but it has been learned that cracks or fractures extending from a well bore out into the earth strata will increase the rate of flow into, or away from, the well under the same pressure differential. The explanation of this increase is simple. A fracture has a much greater ability to transmit fluid than does the usual reservoir rock. According to one authority (Park 1. Jones in Petroleum Production, vol. 1, Rheinhold Publishing Corp., 1946) the permeability of a fracture is 54,000,000 W darcys where W is the width of the fracture in inches. Thus a fracture having a width of 0.01 inch would have a permeability of 5,400 darcys, while the permeability of many commercial oil producing formations is less than 0.1 darcy. Calculations, based upon this, indicate that the controlling factor for obtaining increased flow into, or away from, a bore hole is the length of the fracture. This is true because resistance to flow within the crack is almost negligible, and also the distance which fluids must flow within the natural pores is reduced by increasing the length of fractures.

In preliminary tests made by me employing a model wedgeand-feathers apparatus of the form A, but with a wedge inches long, having a taper of 1 in 40, with the feathers 10 inches long with a one to forty taper on the inside so that the outside diameter of the tool, with 10 inches of the wedge in the feathers, was 1 inches, the radius of cylindrical part of the feathers was inch.

This model permitted constant pressure to be exerted thruout the length of the feathers no 5 matter what was the depth of the penetration of the wedge.

The model apparatus was first tested in a bore drilled in a body of sandstone without visible fracture prior to test fracturing (two northsouth and two east-west) at hydraulic pressures up to 8150 p. s. i. (by the apparatus to be subsequently described), so that the approximate pressure would be known when using the wedge and feathers to extend the fractures. Using a two pound hammer, the wedge was driven down and the operation extended two of the four fractures inches. The east-west fractures which were lengthened were those receiving the main splitting force of the apparatus, but the northsouth fractures opened at the bore hole indicating tension even on the sides in contact with the feathers.

Another bore (bore B) in the same sandstone body was tested using the model apparatus. Table I gives the results.

TABLE I Wedge fracture of bore B Lngtllg of Ratio of rac s, Av Ghau e Wedge O D of Inches g r igg? cha go in T031 Penetra- 6 0 D in Crack 0. D. to tion, Inch m Length, Change E W Inches in Crock Length 0 1 1.601 0 0 0.000 l 1 1 /1 1.638 0 0 0.0375 2% l. 663 0. 0250 8 5 17 3% 1. ass 8 a 0. 0250 0 1. 710 12 12V 0. 0220 3. 7 171 l. 717 13% 14% 0. 0062 2. 1 34.0 1. 732 14% 10 0. 0157 2. 0 127 1. 732 18% 17 0. 0000 2. 3 l. 754 20%: 22 0. 0220 3. 0 164 l. 761 22 23% 0. 0002 l. 5 240 l. 789 24% 24 2 0. 0281 l. 7 62 Average. 163

The test results in Table I indicate that an effective increase of one inch in tool diameter would provide a fracture 163 inches long. This distance probably depends upon the elasticity of the stratum, the more brittle strata having the longer fractures. Forty-seven hours after driving the wedge, with the apparatus in the hole, the fractures had lengthened to an average of 29%; inches. The rock therefore continued to deform under the residual stresses which were set up by the wedge. Using the greater fracture length to compute the length of fracture which would result from a crack one inch wide at the bore hole, gives a length of 716 inches.

Field measurements show that a one inch wide fissure or crack at the bore would extend for substantially to 80 feet to each side of the bore and calculations show that this width of fracture at the bore hole can be obtained by increasing the effective diameter of the apparatus by about 3.71 inches. An increase in the effective diaineter of the apparatus of at least two inches is readily obtainable.

After fracturing has been accomplished re peated blows by the hammer 20 upon the abu ment 32 generally loosen the apparatus from the bore and permit withdrawal as stated.

Referring now to Figs. 7 and 0, there is disclosed a modified form of anchoring means 22 for the feathers, which may be employed in place of the means 20 described. In the use of the means 22, the upper structure l5, jar I6, wedge ll and means I9 are substantially like those employed in the form A.

The feathers 80 employed with the means 22 substantially like the feathers I3 except that the lowermost part of each of the former is modified by removing a section of the lowermost part of each feather body portion to provide an inwardly and downwardly sloping outer face 81 which extends to a substantially horizontal lower end face 99. Extending into the face 81 is a longitudinally-extending relatively narrow slot 89 which initially extends to the face 88 and extends short of the upper end of the face 81 and opens into a recess 99. The recess 90 is wider than the slot 89 and, preferably, slightly longer and also initially extends to the face 80. The slot 89 and adjoining recess 90 are provided for bolt shanks and nuts as shown in Figs. 7 and 8 with the shanks 9I extending into screw-threaded openings in slip bodies 92 and the nuts 93 extending into the recess 90. The nuts 93 are of greater width than the width of their slots 89. Preferably, there are two shanks 9| and nuts 93 for each sliding connection of the two slip bodies 92 and two feathers 86.

The two slip bodies 92 are somewhat triangular in vertical cross section with an outer arcuate face 92 lower face 92 and inner arcuate face 92 sloping upwardly from the face 92 toward the face 92 The face 92 slides vertically over the face 91 of the feather while the shanks 9| slide along the slot 89 and nuts 93 along the recess 99. In order to close the lower ends of the slot and recess, suitable plugs 94 may be provided and secured, as by screws to the feathers 99, after the nuts and shanks are inserted into the recesses and slots.

A separate double hinge structure 95 hingedly connects each slip body 92 to an elongated leg structure 96 with one leaf 95 of the hinge structure 95 fixedly secured to a slip body to extend over the face 92 and the adjacent leaf 95 extending to a leg 99 with which it is pivotally connected as by a pintle 95. Normally, the hinge structure is disposed as in Fig. '7 with the knuckles of the leaf 95 and the leg structure 96 (connected by the pintle 95) resting upon the lower face of the plug 90 and the leg of the leg structure 99 extending downwardly and outwardly (normally, the lower or free end of the leg structure 96 is outwardly of the vertical plane of the outer arcuate face of the upper portion of the feather 89 and in frictional contact with the wall of the bore).

Each leg structure preferably includes a pair of springs 9? extending from one leg to the other, intermediate their lengths normally urging the legs outwardly.

Associated with each hinge structure and leg structure is a resilient means 98 to prevent the hinge structure 95 from closing (to the position shown in Fig. 8) while the apparatus is being run into the well bore. This may comprise two leaf springs secured at one end of each to a feather and with their free ends projecting downwardly and outwardly from the lower flat faces of the feathers and bearing against the leaf 95*. However when the apparatus is moved upwardly when in the desired position for setting, this will overcome the resilient grip of the springs on the hinge structures and the hinges and leg structures will be released and lowered,

causing the hinge structures to close and the leg structures to take positions, similar to the position of the leg structure 96 in Fig. 8. Since the leg structures engage the wall of the bore and the hinge structures have folded against the slip bodies lower faces 95 movement of the feathers 86 downwardly will cause upward sliding movement of the slip bodies over the feathers until the outer faces 92 of the former engage the wall of the well bore. The feathers are then anchored in place and the apparatus manipulated as heretofore described to spread the feathers to cause fracturing of the stratum.

Referring now to the form B illustrated in Figs. 9 and 10, this apparatus for fracturing the stratum surrounding a well bore by exerting mechanical pressure against the wall of the bore, comprises an upper support structure I99, supporting an expansible and contractable structure IOI functioning somewhat like the expansible and contractable feathers I9 of the form A.

The upper structure I90 comprises the upper portion of an elongated tubular member Hi5 provided with a restricted passageway I05 which may be formed by inserting a perforated plug I91 into the bore of the member I95. Below the plug I01, the member I05 is provided with pressure fluid passageway I00 thru its wall and the member I95 may be closed, at its lower end, by a suitable plug I09.

The member I05 supports a flexible, substantially fluid-tight sleeve IIll comprising a wall of suitable material, the ends of which sleeve may be secured to the member I95 as by the two spaced-apart flanged members III which may have their ring portions H2 welded or otherwise secured to the member I05 so as to project outwardly beyond the periphery of the latter. Extending from each ring portion III is a flange H2 in gripping relationship with the ends of the sleeve. Between these ends and the outer face of the wall of the member I95 may be a cornpressible ring packing IM. This provides an annulus H5 defined mainly by a portion of the wall of the member I05 and sleeve H0.

The sleeve H0 may be of rubber (natural or synthetic) or heavy canvas, folded upon itself when the sleeve is not expanded. An example of a useful synthetic product is the neoprene compound having a tensile strength of 1400 p. s. i., an elongation of 820% and a durometer hardness of 47-62.

Fluid under pressure, entering the annulus from a suitable source, thru the member I09 and passageway I09, will cause expansion of the wall of the sleeve I I0 against the wall of the bore and cause cracks or fissures. Such cracks or fissures 95 in the stratum E surrounding the well bore 89 are shown, by way of example, in Fig. 10.

Obviously the apparatus of form B may be lowered and raised by being attached, in any conventional manner, to the well tubing and the pressure fluid introduced by way of this tubing. A separate means for introducing the pressure fluid is disclosed in connection with the form C of the invention to be subsequently described.

Tests were made with a model apparatus constructed in accordance with the above specification of form B, employing hydraulic pressure, and made in a bore drilled in the center of a large continuous block of sandstone measuring about 36 feet by 42 feet, without visible fracture, and surrounded for a. distance of feet, or more of the same strata in every direction. Except for vertical load the best test was under conditions identical with those in an oil field. Rupture began at 5460 p. s. i. with two slight fractures about 4 inches long. No further fracturing occurred until the pressure reached 6100 p. s. i. when two more fractures, all at right angles formed. Upon gradually increasing the hydraulic pressure to a maximum of 8156 p. s. i. which was somewhat above the safe limit of the equipment, the cracks widened and elongated with the increase in pressure. average length of the cracks was 28 inches.

Referring now to the form C, illustrated. in Figs. 11 and 12, this apparatus for fracturing the stratum surrounding a well bore by exerting mechanical pressure against the wall of the bore, comprises an upper support structure IE which carries an expansible and contractable structure lib as well as novel means ii? for introducing the pressure fiuid to the structure I lit.

The upper structure H5 shown in Fig. 12 includes a tubular element I23 having interior screw threads ii! at its upper end portion and interior screw threads H2 at its lower end portion. Preferably the intermediate portion of the tubular element I29 has a smooth bore. Cooperating with the screw threads iZI are the exterior screw threads of plug E23 having an axially-disposed screw threaded socket [2 3 extending from its upper or outer face 525 toward its lower or inner face I25 and a conduit-accommodating bore I2? extending from the face to the face 526. Cooperating with the screw threads H22 is an adapter 528 having a body portion lit provided with an axially-disposed, screw threaded bore ltd to receive a portion of the expansible and contractable structure lit. By this construction, a compartment Iti is provided, defined by the plug I25, adapter I28 and portions of the walls of the tubular element IN to house a portion of. the means i I7.

As shown, mainly in Fig. 11, the expansible and contractable structure H5 includes a central, preferably cylindrical body I35 provided with screw threads are at its upper end portion to cooperate with the screw threads of the bore l 3i! of the adapter. Extending inwardly from the upper face i375 oi the body I35 is an axially-disposed, screw threaded tapered socket I33 to receive a portion of the means Ill to be described. From the base of the socket it? a pressure fluid passageway extends axially of the body I135 to short of its lower end, whereupon the passageway l3 projects radially of the body to outer side face, where it opens into an annulus Mil defined by portions of this face and a contractable and expansible sleeve Hi the wall of which may be substantially like the wall of the sleeve II ll, except that, if desired, the sle vs as! may gradually incr ase in wall thickness from its ends toward its central portion The sleeve Ml is retained in place about the body by spaced-apart flanged members its clamped against the ends of the sleeve Mi. Each member hi3 comprises a. ring portion M 2 welded or otherwise secured to the body M5 and a flange i l-5 extending along the sleeve MI for a short distance and gripping the same. These flanges extend toward each other. Ring packing Mb may be disposed between the sleeve Mil and body F55, as shown in Fig. 11.

The flanged members M3 have dual functions in that each supports an end portion M? of a helical spring This end portion Ml may be fixedly secured to a flange I45. Preferably, the convolutions of each spring M8 are angular in transverse cross section and the spring gradually decreases in cross sectional area and increases in width of convolution from the attached end portion [41 to the free or thinnest end portion Hill, which latter may be disposed adjacent the central portion Hit of the sleeve. The spring I48 grips the end portion or the sleeve, and it is so constructed that, as the sleeve ex- ,pands the former will also expand diametrically, being free at its end P39, and it will be this free end and adjacent portions of the spring which will expand to a greater diameter than the portions adjacent the flange M5. There will be, in fact, a tapering of the periphery of the spring from adjacent the flange I to the free end of the spring and this aids in preventing the flange from cutting the adjacent portions of the sleeve and also aids in preventing the ends of the sleeve from being forced, by the fluid pressure, from their contact with the member I35 and flange M5.

The means II! for introducing the pressure fluid to the structure I It is shown in the upper portion of Fig. 12, and includes a suitable connection I50 having a screw threaded shank portion or nipple It! for insertion into the screw threaded socket I38 so that the connection I50 may be coupled to the member !35 and disposed within the compartment I3I. The connection. l 59 has a pressure fluid passageway I52 from end to end and a branch pressure fluid passageway its extending from the intermediate portion of the passageway I53 to the upper face Ifit of the connection. From the upper end of the passageway I53 a conduit I55 extends thru a sleeve I56 and is closed at its upper end by a. frangible element I5l.

The sleeve ltd is, preferably, of substantial construction of sufficient strength to support the weight of the structure below it, and it is screw threaded both ends. The lower screw threads. cooperate with the screw threads I241 of the plug I233.

The frangible element l5! may comprise a thin, metallic disc 1158 having an axially disposed reduced portion I55 with the disc disposed over the upper end of the conduit I55.

Preferably, the element I 51 is held in place in a recess Bil in the lower end of a packing gland It! which screws into a screw threaded recess I62 in the upper end portion of the sleeve 558, and with a smaller-diametered packing gland 133 screwed into a screw threaded recess IM- in the upper end portion of the gland Iflii and bearing upon the upper face of the disc I58 adjacent its periphery, a suitable packing 565 being interposed between the lower end of the gland Hi3 and disc M5. The passageway I66 thru the gland I553 accommodates, at its lower end, the reduced portion i553 of the frangible element ifit. Bestupon the top of the reduced portion is a pin it? which extends upwardly thru the passageway I86 (and is freely slidable therein) and outwardly of the upper end of the gland H33 where it ends in a head Hi8. This construction is provided so that a conventional go-devil (not shown) may be dropped to strike the head its and force the pin Nil to rupture the frangible element.

The go-devil may be dropped thru the conven tional oil well tubing I69, the lower end of which has its screw threads coupled with the exterior screw threads at the upper end portion of the sleeve I56. This tubing I69 may be employed for the upward flow of the released pressure fluid.

Again referring to the branch pressure fluid passageway I53 in the connection I50, a pressure fluid conduit us extends from this passageway, upwardly thru the compartment [3| and bore I27 to outwardly and upwardly of the plug l23 where, by conventional coupling means 51!, it is coupled to a conduit I12 which may extend parallel to the tubing I69 and to the mouth of the well bore. Fluid under pressure flows thru the conduit I12, coupling means Ill, conduit I10, connection I50 and passageway I39 to expand the contractible and expansible structure H6.

' Of course, the devices disclosed by the several forms of the invention encounter the fluid (liquid and gas here) usually found in oil wells but such fluid is not a hindrance to the successful operation of the several devices. In fact, the hydrostatic pressure of this fluid in the well bore will exert a force on the walls 85 of the crack. Pressure applied to the fluid in the annular space around the member I05 would augment this force and assist in fracturing as soon as an initial small opening were formed.

' What is claimed is:

1. In apparatus for fracturing t e stratum forming the wall of a well bore, a support rtructure including a tubular member provided with a pressure fluid passageway and an opening to the exterior of the member intermediate its ends; an expansible sleeve structure of flexible material, having a well bore wall-engaging outer face and opposite end portions, said sleeve structure including a fluid tight portion and an outer portion said outer portion comprising a pair of helical springs, the portion of said face engaging said wall being of material which, when pressed against said wall by fluid pressure will cause said wall to fracture; and means to secure the end portions of said sleeve structure to and around that portion of said tubular member at and adjacent said opening, said means being spaced from said opening and being a substantially fluid-tight means, said means including spaced-apart members, one secured to one end of one of said helical springs and the other secured to the like end of the other helical spring, the opposite end of said springs being free and spaced intermediate the length of said fluid-tight portion.

2. In apparatus for fracturing the stratum forming the wall of a well bore, a support structure including a tubular member provided with a pressure fluid passageway and an opening to the exterior of the member intermediate its ends; an expansible sleeve structure of flexible material, having opposite end portions, said sleeve structure including a fluid tight portion and an outer portion said outer portion comprising a pair of helical springs, each convolution of each spring being of springy material having a plurality of substantially flat face portions, with a flat face portion of each convolution facing outwardly of said springs and constituting a face portion engaging said wall, the portion of said face engaging said wall being of material which, when pressed against said wall by fluid pressure will cause said wall to fracture; and means to secure the end portions of said sleeve structure to and around that portion of said tubular member at and adjacent said opening, said means being spaced from said opening and being a substantially fluid-tight means, said means including spaced-apart members, one secured to one end of one of said helical springs at a flat face portion of said one of said spring and the other secured to the like end of the other helical spring at a flat face portion of said other helical spring,

the opposite ends of said springs being free and spaced intermediate the length of said fluidtight portion.

3. In apparatus for fracturing the stratum forming the wall of a well bore, a support structure including a tubular member provided with a pressure fluid passageway and an opening to the exterior of the member intermediate its ends; an expansible sleeve structure of flexible material, having opposite end portions, said sleeve structure including a fluid tight portion and an outer portion, said outer portion comprising a pair of helical springs, each convolution of each spring being of springy material and having a plurality of substantially flat face portion, with a flat face portion of each convolution facing outwardly of said springs and constituting a face portion engaging said Wall, with another flat face portion of each convolution facing inwardly and in face contact with said sleeve structure, the portion of said face engaging said wall being of material which, when pressed against said wall by fluid pressure will cause said wall to fracture; and means to secure the end portions of said sleeve structure to and around that portion of said tubular member at and adjacent said opening, said means being spaced from said opening and being a substantially fluid-tight means, said means including spaced-apart members, one secured to one end of one of said helical springs at a flat face portion of said one of said spring and the other secured to the like end of the other helical spring at a flat face portion of said other helical spring, the opposite ends of said springs being free and spaced intermediate the length of said fluid-tight portion.

4. In an apparatus for fracturing a stratum forming the wall of a well bore, a support structure including a tubular member provided with a pressure fluid passageway having an opening to the exterior of the member intermediate its ends; an expansible sleeve structure of flexible material surrounding said tubular member, said sleeve structure having opposite end portions inclosing, in a fluid tight relationship, that part of said tubular member about said opening, and a helical spring comprising a plurality of interconnected convoluticns of resilient material surrounding said expansible sleeve structure and capable of effectually resisting disruption when forced against said stratum with stratum-fracturing pressure, said convolutions ending short of the middle of said expansible sleeve structure in a free end convolution; and means securing the convolution of said helical spring most remote from said free end convolution to and around an end portion of said sleeve.

5. In apparatus for fracturing a stratum forming the wall of a well bore, a support structure including a tubular member provided with a pressure fluid passageway having an opening to the exterior of the member intermediate its ends; an expansible sleeve structure of flexible mate rial surrounding said tubular member, said sleeve structure having opposite end portions enclosing, in a fluid tight relationship, that part of said tubular member about said opening, and a helical spring surrounding said sleeve structure, said spring comprising a plurality of interconnected convolutions of resilient material capable of effectually resisting disruption when forced against said stratum with stratum-fracturing pressure, said convolutions ending, short of the middle of said expansible sleeve structure,

in a free end convolution; and means securing the convolution of said helical spring most remote from said free end convolution to and around an end portion of said sleeve, the other of said convolutions including the first-named convolution being freely movable over the outer surface of said. fluid tight portion.

References Cited in the file of this patent UNITED STATES PATENTS Number Re. 5,434

Number 14 Name Date Pitzer Feb. 13, 1940 Haynes Aug. 23, 1921 Robinson Nov. 13, 1923 Clifford May 31, 1927 Frantz June 2, 1931 Litolf Nov. 26, 1940 Maloney Sept. '7, 1943 Garrison July 3, 1945 Lehnhard Apr. 23, 1946 Clark May 13, 1952 

